A conventional power conversion device includes: a converter (main converter) composed of four switch elements; a smoothing capacitor for smoothing output of the converter; a single-phase inverter (sub converter) composed of four switch elements and a DC capacitor and having one AC terminal connected to an AC terminal of the converter; and a reactor connected between the AC terminal of the single-phase inverter and the AC power supply (see, for example, Patent Document 1).
The converter is driven by gate pulses with 1 pulse per half cycle of the AC power supply, to operate so that generated voltage at the AC terminal of the single-phase inverter becomes a difference between voltage of the AC power supply and generated voltage of the AC terminal of the converter, thereby reducing voltage applied to the reactor and controlling the power factor for voltage and current of the AC power supply so as to be a high power factor while controlling voltage of the smoothing capacitor to be a desired voltage.